Fluctuation-damping means for rotatable members.



P. M. RMNEY. FLUCTUATION DAMPING MEANS FOR ROTATABLE MEMBERS APPLICATIONFILED DEC.26.1914.

Patented July 2, 1918.

VV/fnesses:

UNITED STATES PATENT OFFICE.

PAUL M. RAINEY, OF GLEN RIDGE, NEW JERSEY, ASSIGNOR, BY MESNEASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OFNEW YORK.

FLUCTUATION-D AMPING MEANS FOR ROTATABLE MEMBERS.

Specification of Letters Patent.

Patented July 2, 1913;

Application filed December 26, 1914. Serial No. 879,040.

To all whom it may concern:

Be it known that I, PAUL M. RAINEY, a citizen of the United States,residing at Glen Ridge. in the county of Essex and State of New Jersey,have invented certain new and useful Improvements in Fluctuation-DampingMeans for Rotatable Members, of which the following is a full, clear,concise, and exact description. I

This invention relates to means for damping out the speed fluctuationsof a rotating system, and has for its object the production of dampingforces acting upon rotating members to minimize or prevent excessivespeed fluctuations therein due to disturbing influences whereby anyincrease or decrease in speed of the rotating system will be a gradualone. The disturbing influences tending to cause the rotating members tofluctuate may vary in range and may be due to inherent characteristicsof the driving means, such as the tendency of a synchronous motor tohunt or they may be caused by extraneous forces.

In accordance with the general characteristics of this invention, whatin the system may be considered the main rotating member is suppliedwith a damping device, comprising two fly-wheels having differentcharacteristics, operating to dampen out or prevent undue fluctuationsby the production of frictional'efi'ects which may be called dampingfriction. One of thefly-wheels is so constructed and associated with themember that the damping friction produced by it is at a minimumwhenthere'is no relative movement between them, but increases with anychange, however slight, in the relative movement of the two. Thisdamping friction, starting at a minimum, increases as the relativemovement between this fly wheel and the member increases. The relativemovement depends upon the rate or acceleration at which the fluctuationof the member takes place and the friction between the member and thefly wheel, and since this fly wheel is to be eflicacious for small speedvariations, the initial or static friction should be relatively small.Since it has been found by experiment that it is objectionable toconstruct a fly wheel possessing the above characteristics which willeffectively dampen the greater fluctuations, a second fly wheel isprovided. With this second fly wheel, on the other hand, the dampingfriction produced should be relatively high at the in-' eration ofparts, the first fly wheel tends to dampen out even the most minutefluctuations, being assisted by the second fly wheel only when thefluctuations are suflicient to overcome the static friction between thesecond fly wheel and the member, such fluctuations being too great to beeffectively damped out by the action of the first fly wheel alone.

The first fly wheel is preferably an annular body of liquid, thecontainer of which is secured firmly to and preferably forms a part ofthe rotating member. It is a wellknown physical fact that the frictionbetween a liquid and a solid, with which it is in contact, is zero whenthere is no relative movement between them, and that the frictionincreases as the relative movement increases. An annular body of liquid,therefore, most admirably meets the conditions required of the first flywheel. The other may be an ordinary solid fly wheel frictionallyconnected with the rotating member in such a manner that it may be movedindependently thereof. With this arrangement the damping friction isgreatest at the instant relative movement begins, and decreases as tlerelative'movement increases. Means may be provided for varying thefrictional engagement of the solid fly wheel and the rotating member toany desired amount.

For convenience of illustration, the invention is shown as applied tothe shaft 5 of a synchronous motor 6 which may be of the phonic or LeCour type, and which is connected to drive a brush distributer 7, suchas are familiar in the printing telegraph art. It is obvious, however,that the invention is not limited in its application to the illustrateddevices.

As will be noted, the shaft 5 of the motor 6 is extended a distancebeyond the end of the frame and has secured thereto by means of a key 10a sleeve 11. Secured firmly to this sleeve 11 is a cylindricalcontaining member 12 having a screw-threaded hub 13 and a flange 14. Theinner surface of the flange 14 is slightly tapered to receive a taperedclosing member 15 which is threaded upon the hub 13 to form with theinterior of said casing member 12 an annular chamber 16 into whichmercury or other suitable liquid may be inserted through openingsnormally closed by plugs 17, 17.

Rotatably mounted upon an extension 20 of the sleeve 11 is a solid metalfly wheel 25 of considerable inertia. Interposed between the adjacentfaces of the two fly wheels is a washer 26 of felt or any other suitablematerial for creating friction between said fly wheels. The pressurebetween this washer 26 and the two fly wheels may be regulated by meansof a tensioning spring 27 and adjusting nuts 28 and 29 therefor.

While the fly Wheel 25 is shown as embracing the container of the liquidfly wheel and frictionally connected with the shaft 5 through one facethereof, this is merely for the purpose of economy in space, as it isobvious that the same results would be obtained if the fly wheel 25 wasmounted a distance away from the liquid fly wheel on the shaft and otherforms of frictional connecting means between the fly wheel 25 and theshaft 5 were provided.

The damping friction between the liquid and the shaft 5 through thewalls of the container is at a minimum when there is no relativemovement between the liquid and the container but increases as therelative movement between the two increases. The damping frictionbetween the fly wheel 25 and the shaft 5 is at a maximum at the momentrelative movement between the shaft and the fly wheel begins, anddecreases as the relative movement between the two increases. With thisparticular combination of fly wheels it has been found possible todampen out all fluctuations or vibrations of a rotating shaft so thatany increase or decrease in speed will be at a uniform rate.

What is claimed. is:

1. The combination of a rotatable member subject to speed fluctuations,with means forproducing damping friction to dampen out saidfluctuations, comprising two fly wheels of different characteristics andcapable of relative movement with res ect to said member, the relativemovement bein caused by speed fluctuations, the damping flrictionproduced by one of said wheels being relatively small when such movementbegins and the damping friction produced by the other of said fly wheelsbeing relatively large when such movement begins.

2. The combination with a rotating member subject to speed fluctuations,of means for damping the fluctuations of said rotating member comprisinga pair of independently operable fly wheels, the damping frictionbetween one of said fly wheels and said member increasing, and thedamping friction before the other of said fly wheels and said memberdecreasing as the relative movement between the respective fly wheelsand said member increases.

3. The combination with a rotating memher subject to speed fluctuation,of means for damping out said fluctuations, said damping meanscomprising a liquid fly wheel the container for which is secured rigidlyto said member and a solid fly wheel frictionally secured to said memberwhereby it may rotate independently thereof.

4. The combinationwith a rotating memher subject to speed fluctuation,of means for damping out said fluctuations comprising a liquid fly wheelthe container for which is fixed to said member, a solid fly wheelmounted upon said member, frictional connecting means interposed betweensaid solid fly wheel and said member, and means for varying the pressureupon said frictional connection.

5. The combination with arotating member subject to speed fluctuations,of means for applying said rotating member in accordance with thefluctuations thereof, damping effects presenting diflerentcharacteristics for damping out said fluctuations.

6. The combination with a rotatingmember subject to speed fluctuations,of means for damping out said fluctuations comprising two independentlyoperable fly wheels of different characteristics, each fly wheelproducing its maximum damping effect when k the damping effect of theother fly wheel is at a minimum.

- In witness whereof, I hereunto subscribe my name this 24th day ofDecember,

PAUL M. RAINEY. Witnesses:

E. EDLER, K. L. Sum.

